CRPS – Complex Regional Pain Syndrome, (previously known as RSD, Reflex Sympathetic Dystrophy) is a frustrating, chronic and painful condition in which the central nervous system continues to send nerve signals indicating pain long past the time that healing of an injury or surgical procedure has occurred. CRPS is characterized by prolonged or excessive pain and changes in skin color, temperature, and/or swelling in the affected area. The syndrome typically affects a limb.